By Mitchell Zimmer Richard Léveillé’s research has come full circle. Ten years ago he was finishing his PhD in the Earth Sciences Department at Western studying a group of clay minerals known as magnesium phyllosilicates in Fred Longstaffe’s laboratory. Now, as a member of the Canadian Space Agency he is participating in the Mars Science Laboratory mission. He is searching for these same minerals to find out if water had a role in the planetary history of Mars.Alumnus Léveillé looking for rock hard evidence of water on Mars
Léveillé’s proposal is one of two selected by NASA with a Western connection. (John Moores, a postdoctoral fellow at Western’s Centre for Planetary Science and Exploration is the other), Only 29 proposals in total were chosen. He says that writing this proposal “was a little bit a challenging….One thing that encouraged me, NASA was looking for people who had no previous mission experience. . This is certainly a career objective to work on a planetary mission.” When word came that his proposal was selected, Léveillé admits that he was a bit surprised, “I knew it was a ‘this changes everything’ kind of news. As I was told by one of my colleagues ‘Wow, this is your TSN turning point.’ This will be a big part of my professional career for the next few years.”
Léveillé says that his proposal is focused on looking for mineral indicators where water and fairly benign conditions for life as we know it could be found. He’s searching for magnesium phyllosilicates specifically because these “minerals are generally formed in places where there is quite a bit of water so it’s more to do with the environment of formation.”
Evidence of Martian clay minerals already exists says Léveillé. “We know there are some there, we can detect them from the rovers that are there now, although not too well, but also see them from orbit from spacecraft.” So far, the majority of the finds are “iron and magnesium rich clay minerals and aluminum rich clay minerals. These are all to be expected if you take the starting material on Mars which … contains iron, magnesium, aluminum and silicon and if you alter that with a bit of water you will most likely produce some phyllosilicates.” There is an important difference in the case of the magnesium phyllosilicates. Since magnesium and silicon are more soluble than iron and aluminum, a lot of water has to react with the rock to transport the magnesium and the silicon away to be deposited somewhere else.
That’s why the rover Curiosity is scheduled to land at the Gale Crater on Mars. “The Gale Crater is an interesting place and among other things it may have hosted some lake deposits which would have eventually evaporated, frozen or maybe sublimated,” says Léveillé. ”It certainly had processes there where presumably you had a body of water at least in parts of Gale that is no longer there but could have left some kind of sedimentary deposit including these magnesium rich clays. In fact, magnesium clays are often found in paleolake deposits or old lake deposits around the world.”
“If we get there and we find mostly basaltic rocks that have been a little bit altered and there is some iron-magnesium clays and some aluminum clays, and not much else, that’s going to indicate that there probably wasn’t that much water…. But if we find these magnesium clays and if they’re with some carbonate minerals or some gypsum that would tend to indicate a lot of interaction with water with the rock.” If the Curiosity can find a sedimentary record of different layers, then it will be possible to determine if there was a significant period in Mars’ history where these conditions existed and created a chemical reaction which offered potential energy resources for microorganisms. “That is a big part of the mission,” says Léveillé, “to look at the habitability of Mars and to understand if different environments existed over different time scales and how the planet evolved over time.”
There is a lot of work to do between now and the August 6 landing. Léveillé will be involved with some pre-mission field work using portable instruments that are, in some cases, quite comparable to what Curiosity has on board and also in laboratory studies on some minerals. He’ll be looking at differences in chemical composition, X-ray diffraction signatures and other analyses to build up a baseline of information so as to get a good idea of what to potentially expect so if they do find it. “It’s going to be a busy mission,” says Léveillé. “One of the instruments, the ChemCam, is a camera with a laser induced break down spectroscopy instrument. It actually zaps a rock with a laser and it can determine the elemental compositions of that rock up to a distance of about seven meters, so this instrument will probably be used on most days… that’s one I hope to be using a lot.”
This work could also reunite Léveillé with Fred Longstaffe. Longstaffe still has data samples remaining from the time Léveillé was working in his lab, “We’re going to try to see what that data says and whether it can help in any way with what I’m doing now on this mission. I was very happy to touch base with Fred and possibly working with him again.”
